Automatic control



June 1945- c. F. KETi'ERlNG ET AL 2,377,698

AUTOMATIC CONTROL Filed Aug. 3, 1942 2 Sheets-Sheet 2 Imnentors Patented June 5, 1945 Charles F. Kettering and Albert W. Fischer. Dc-

trait, Mich, assignors to General Motors Cornotation, Detroit. Mich, a corporation of Dela.-

ware,

Application. August a, 1942, Serial no. 453,351

7' Claims.

l'his invention relates to automatic control means and more specifically to means toautomatically maintain a mobile body on a predetermined or set course. the operation of mobile craft,- such as ships. or airplanes, it is very desirable to have thereon means. which may be set to hold a course and to have this means automatically maintain such course for a period of time. By some means, such as the above, the operators or pilots thereof are relieved of much tedious duty or such automatically controlled craft may be preset and dispatched with no personnel on board and will reach its objective as in the case of a torpedo.

It is therefore an object of'our invention to provide means that will automatically maintain a self -propelled bodyon' a predetermined set course.

It is afurther object of ourinvention to provide automatic steering mean which requires no attention after it has been set.

It is a still further object of our invention to provide automatic steering means that is simple and rugged.

With these and other objects in view which will become apparent as the specification proceeds, our invention will be best understood by reference to the following specification and claim and the illustrations in the acompanying drawings, in which:

Figure 1 is a schematic view showing the essential parts of our control system;

Figure 2 is an enlarged sectional view taken on line 2--2 of Figure 1;

Figure 3 is a circuit diagram of the electrical connections of our invention;

Figure 4 is an enlarged vertical section through the compass unit;

Figure 5 is a sectional view taken substantially on line 55' of Figure 6';

Figure 6 is a horizontal section taken on line 66 of Figure 4; and,

Figure '7 is a top detailed view of the master compass magnets and their mounting.

Referring now more specifically to the drawings, there is shown in Figure l steering mechanism indicated generallyat 2 for operating the rudder of a. self-propelled craft such as a boat or plane. A driving motor 4 is utilized to physically turn the steering mechanism and thus the rudder to predetermined points and this motor is avsmall reversible one which is upplied by power from a suitable power source 6 which in Figure I also houses necessary amplifying apparatus. The means for maintaining the steering mechanism and the rudder in the necessary positions is primarily a compass unit indicated generally at 8 which through means to be described controls the motor 4 to set the rudder;

The particular steering mechanism in this instance is disclosed for purposes of illustration only as being a steering wheel of a boat which wheel is mounted upona shaft t0 connected to the steering mechanism or rudder by suitable means not shown. This shaft ll carries a sprocket wheel l2 loosely mounted on the shaft inside of the head It of the steering wheel per se I6. A collar I'lfl-tti ng' inside the steering wheel and surrounding the hub of the sprocket I2 is mounted on the steering wheel through spaced peripheral pins to connected toa disc 22 on the outer face o1 the steering wheel. This disc 22 has; a central opening 24' therein which is internally threaded and through which a thumb screw 26 is inserted to press against the hub of the steering wheel to cause-the assembly to be pulled outwardly.

To the face of the hub of the sprocket I2 is positively secured by rivets a ring 28'. and to the inner face of the steering wheel and in alignment with the ring 28 is rigidly secured a collar 30 of friction material such as brake lining. Thus when the screw- 26 is manually forced against the hub of the Wheel, the collar l8 is pulled outwardly and locksthe ring 2 8 against the friction material 30 so that the sprocket wheel l2. will rotate with the steeringwheelatall times. This is necessary to allow: at certain intervals relative motion between the wheel and sprocket so that adjustments may be made.

A driving chain 32" indicated by the dotted lines in Figure 1 is fed over the sprocket l2 and also over a second sprocket 34 on the motor shaft, whereby as the motor turns, the steering wheel and rudder will also be turned or adjusted. A plurality of flexible drive meansare also driven by the motor 4, one of which comprises a Bowden wire connection 38 between the motor and an indicating member 40. Thus as the motor 4. rotates, such rotation will actuate:- the indicating apparatus: 40 to inform the operator: as. to the course upon whichthecontrol is set and which will be followed. At the same time a follow-up mechanism for the compass is operated: through flexible drive 36.

The compass mechanism per so which has been indicated generally at 8 consists ofa substantially cylindrical housing #1? which is covered bya cap 44. A supporting cross panel 43 is: provided in the base of the cylindrical: member and perma nently fixed therein. This base has a central aperture therein in which is mounted a bushing 48 through which a. short stub shaft 50 projects. Mounted upon the inner or upward end of the shaft 50 is a disc member 52 of only slightly smaller diameter than the casing. This disc carries about its periphery a drum 54 formed of insulating material and in the exterior surface or" this drum are carried spaced conductive rings 56 providing sliding contactors for a series of sprin biased terminals 58 which cooperate therewith, said terminals 58 being connected to individual wires provided in a connecting cable 60 which conducts them back to the power supply and amplifier. Thus as the stub shaft 50 turns, all of the mechanism carried thereby will also have its angular position altered. The terminals 58 are carried in the side of a casing by an insulating block6I and have portions bearing against the surface of these circular conductive inserts in the insulating drum 54. Thus any power from other parts of the apparatus is conducted to mechanism carried by the rotating means through the terminals and conductive rings.

On the lower end of the stub shaft 50 there is secured a gear 62 which is connected to the rotating shaft 50 and engages the gear driven by the Bowden wire means 36 and is therefore driven by the motor 4 in its rotation. Secured to the upper face of the disc 52 is a. flanged bell member 64 which has stretched across its inner portion a corrugated diaphragm member 66 to seal the same from the atmosphere. The central portion of this bell at the top is provided with an opening through which a hollow bushing 68 passes, said hollow bushing securing a large hollow spherical body thereto. In the hollow section of the upper portion of the bushing 68 is inserted one end of a tapered rod I2. On this rod at substantially the midpoint thereof is fastened a disc I4 and a concentric coil spring 16 is mounted around the rod bearing against, the disc I4 and a shoulder on the outer urface of the bushing 68. This tends to eject the rod from the bushing or force it upwardly as shown in Figure 4 to provide a spring mounting for means to be described.

The spherical member I0 and the interconnected enclosure formed by the bell member 64 and diaphragm 66 which forms an auxiliary expansion chamber are adapted to be filled with a fluid l8 and in this fluid bath and pivotally mounted upon the upper end of the tapered rod 12 is a hollow circular member 80. The circular member 80 has a concave conical opening in the buttom surface into the extremity of which the tip of the tapered rod I2 projects and upon which the member 80 i balanced on this pivot point. The member 80 is sealed and therefore maintains air therein and carries on the inner surface of the conical portion a pair of spaced parallel ma nets 82 and 84 which are clamped thereto by small collars 86. These two magnets are built up of Alnico portions 88 and 80 separated by a soft iron spacer 92 to form north and south poles.

The float or member 80 is submerged in the liquid 18 to buoy up approximately 90% of the weight of the magnet assembly and the taper on the conical reentrant opening in the bottom face of the assembly is designed so that the float may pivot in any direction from vertical. Vanes 94 are provided upon the outer surface of the member 80 to furnish damping for movements of the magnet housing. The two magnets 82 and 84 are parallel and when placed in the earth's magneticfield tend to align themselves and the float therewith to indicate direction. Spaced above each of the master magnets 82 and 84 and aligned therewith are two auxiliary magnets 96 and 98 which are supported from the inner surface of the float 80 and are directly above the other two magnets.

The upper surface of the substantially spherical member 10 is depressed to form a hollow portion and in the center of this hollow portion there is pivotally mounted a small vertical rod I00 which carries thereon a mirror I02. A transverse bar I26 is centrally affixed to the vertical rod I00 and carries at its outer extremities two small lave magnets I28 and I30 whose position is controlled by the larger magnets and which do the actual turning of the mirror for control purposes. The lower end of this rod is pivoted at I04 which is the center of the depressed portion and a bracket I06 connected to the upper surface of the member 10 carries the upper pivot I08 which is adjustable to allow the shaft to b clamped firmly but to pivot freely in its two aligned pivots.

A small platform H0 is also carried by the upper surface of the member I0 and an upturned fiange I I2 carries a light I I4, the rays from which project through a panel I I6 having an opening I I8 therein. These light rays fall upon a pair of lenses I20 which project them onto a reflecting surface I22 which surface is concave and converges the rays upon the adjustable mirror I02 whose position is determined by the compass means. The rays are then caused to fall upon a photoelectric cell I24 or similar light sensitive device, the output of which is fed through the terminals to the amplifier. Thus the position of the mirror I02, as determined by the magnets or compass needles, determines the amount of light falling on the photoelectric cell and the output thereof which is amplified determines the operation of the control motor.

Referring now more specifically to Figure 3, there is shown therein the photoelectric cell I24 which is connected to an amplifier I32 by suitable lines I34 and I36. The light source or bulb H4 is connected across the power source by lines I38 and I40. A battery I42 provides the energy for the system and is connected to the amplifier by lines I44 and I46. The output of the amplifier is connected to two relays I48 and I50 in series by lines I52, I54 and I56. Relay I48 operates an armature I51 and relay I50 perates an armature I56. When the relays are energized, the armatures are in their lower position, and when deenergized, in their upper position. Both armatures are spring biased to their inoperative or deenergized position, but the spring bias on armature on I5! is always less than that on armature I58 and therefore with the same current flowing through both relays, armature I51 will be attracted previous to I58.

Armature I51 oscillates between two contacts I60 and I62, the first of which is connected by line I64 to one side of the battery I42 and the second of which is connected by line I66 to contact I68 of the lower armature I58 and also by line I'I0 to line I46. The lower contact I12 of the lower armature I58 is connected to line I64 and thus to the battery. The two armatures I51 and I58 are directly connected electrically to the driving motor 4 of the device.

In operation thereof the compass and indicator are set for a particular course and are adjusted with respect to the steering wheel by unlocking the friction arrangement described and shown in Figure 2 and when they have been set 011 the course the thumb screw to is locked. The device or craft is then started upon its course and the amounts of deviation from said course vary the position of the magnet compass members and 84 and their float with respect to the sub stantially spherical housing "ill. This causes the slave magnets and 430 to move the n. 'rror about its pivot and therefore vary the ass-cunt of light thrown on the photoelectric cell.

The output of said photoelectric cell is fed through the amplif er and applied to the two re lays I48 and led in eries. If the craft has not deviated sufficiently from its course in one direction to warrant correction, the amount of current flowing in the relay circuits will be insufficient to cause them to be attracted and they will therefore have their armatures their upper position and the motor t continues to be energized to turn in one direction through the iollowing circuit: battery M2, line line lot, con-- tact I60, armature motor tarmature lliihcon tact I65, line I Hi, line Hi6, back to the battery I42. This will cause the rudder to turn in one direction.

However, when a sufficient co *rection or movement of the rudder in one direction Las been obtained, the light on the photoelectric cell will become more and more inten e and the current flowing in the relay circuits will increase until such time as relay M8 has a sufficient current to attract its armature 3?. This will break the motor circuit, and since at this instant aanature I58 is still up, no current will flow through the motor. The rudder will then remain in the position set which will probably be to cause the boat to turn further on course and when the light intensity increases still further, the relay I50 will be sufficiently energized to attract its armatures 158 and both armatures lti'l and tilt will now be in their lower or energized position and the motor l will be caused to rotate in the opposite direction to that previously described and. the rudder will be moved back to cause a correction in the opposite direction.

It will therefore be obvious that the control mechanism will cause the motor to move the rudder first slightly in one direction and then slightly in the opposite direction, but this is not strictly a, hunting system because there is a period when one relay attracts its armature and the other does not when the motor has a deenergized or off condition. [is before stated, when the motor i operates it drives the indicator All through a flexible cable drive, and simultaneously through the flexible cable drive 35 causes a worm lit to turn the gear 52 as a follow-up mechanism to adjust the position of the main portion of the compass means to decrease the variation or amount of correction appiled thereby.

We claim: I

1. In control apparatus for self-propelled craft, steering means to direct the course of the craft, reversible driving means for the steering means, and control means operable by various strengths of u; irectional current flow therein to control the driving means and to cause it to reverse as the strength varies between predetermined limits.

2. In control apparatus for self-propelled craft, eriug means to direct th course of the craft, reversible driving means for the steering means, conrol means for said driving means operable not values of a unidirectional current to cause the driving means to reverse and compass controlled means for varying the current intensity.

In control apparatus for self-propelled craft, steering means to direct the course of the craft, reve sible driving means for the steering means, p ality of relays operable at different current values to change the polarity on the driving means cause it to reverse its direction of rotation, and compass controlled means to Vary the fiow cl current to the relay means.

in control apparatus for self-propelled craft, steering means to direct the course of the craft, reversible driving means for the steering means, a plurality of relays operable at different current values to change the polarity on the driving means and cause it to reverse its direction of rotation, a light sensitive means, compass controlled means to vary the amount of light falling thereon to alter the current output and means to connect output to the relay means.

5. In control apparatus for self-propelled craft, steering means to direct the course of the craft, reversible driving means for the steering means, a plurality of relays op rable at different current values to change the polarity on the driving means and ca it to reverse its direction of rotation, a light sensitive means, compass controlled means to vary the amount of light falling thereon to alter the current output, and amplifier means connected to the light sensitive output and to the relay means whereby sufficient current is supplied to the relays to operate them and the current is varied dependent upon the output of said sensitive means.

6. control apparatus for self-propelled craft, means to direct the course of the craft, reversible driving means for said directing means, clutch means interconnecting the two whereby the same may be relatively adjusted and compass controlled means for controlling the driving means to maintain a predetermined course.

2. In control apparatus for self-propelled craft,

-rneans to direct the course of the craft, reversible driving means for said directing means, clutch means interconnecting the two whereby the same may be relatively adjusted, relay means connected to the drive means, amplifier means connected to the relay means and compass controlled means connected to the output of the amplifier whereby the compass means will control the drive means and thus the directing means but adjustment may be made between the directing means and the control means.

CHARLES F. KETTERING. ALBERT W. FISCHER. 

